misc: mic: SCIF fence

This patch implements the fence APIs required to synchronize
DMAs. SCIF provides an interface to return a "mark" for all DMAs
programmed at the instant the API was called. Users can then "wait" on
the mark provided previously by blocking inside the kernel. Upon
receipt of a DMA completion interrupt the waiting thread is woken
up. There is also an interface to signal DMA completion by polling for
a location to be updated via a "signal" cookie to avoid the interrupt
overhead in the mark/wait interface. SCIF allows programming fences on
both the local and the remote node for both the mark/wait or the fence
signal APIs.

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Nikhil Rao <nikhil.rao@intel.com>
Signed-off-by: Jacek Lawrynowicz <jacek.lawrynowicz@intel.com>
Signed-off-by: Sudeep Dutt <sudeep.dutt@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 771 insertions, 0 deletions

diff --git a/drivers/misc/mic/scif/scif_fence.c b/drivers/misc/mic/scif/scif_fence.c
new file mode 100644
index 000000000000..7f2c96f57066
--- /dev/null
+++ b/drivers/misc/mic/scif/scif_fence.c
@@ -0,0 +1,771 @@
+/*
+ * Intel MIC Platform Software Stack (MPSS)
+ *
+ * Copyright(c) 2015 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License, version 2, as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * Intel SCIF driver.
+ *
+ */
+
+#include "scif_main.h"
+
+/**
+ * scif_recv_mark: Handle SCIF_MARK request
+ * @msg:        Interrupt message
+ *
+ * The peer has requested a mark.
+ */
+void scif_recv_mark(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        int mark, err;
+
+        err = _scif_fence_mark(ep, &mark);
+        if (err)
+                msg->uop = SCIF_MARK_NACK;
+        else
+                msg->uop = SCIF_MARK_ACK;
+        msg->payload[0] = ep->remote_ep;
+        msg->payload[2] = mark;
+        scif_nodeqp_send(ep->remote_dev, msg);
+}
+
+/**
+ * scif_recv_mark_resp: Handle SCIF_MARK_(N)ACK messages.
+ * @msg:        Interrupt message
+ *
+ * The peer has responded to a SCIF_MARK message.
+ */
+void scif_recv_mark_resp(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        struct scif_fence_info *fence_req =
+                (struct scif_fence_info *)msg->payload[1];
+
+        mutex_lock(&ep->rma_info.rma_lock);
+        if (msg->uop == SCIF_MARK_ACK) {
+                fence_req->state = OP_COMPLETED;
+                fence_req->dma_mark = (int)msg->payload[2];
+        } else {
+                fence_req->state = OP_FAILED;
+        }
+        mutex_unlock(&ep->rma_info.rma_lock);
+        complete(&fence_req->comp);
+}
+
+/**
+ * scif_recv_wait: Handle SCIF_WAIT request
+ * @msg:        Interrupt message
+ *
+ * The peer has requested waiting on a fence.
+ */
+void scif_recv_wait(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        struct scif_remote_fence_info *fence;
+
+        /*
+         * Allocate structure for remote fence information and
+         * send a NACK if the allocation failed. The peer will
+         * return ENOMEM upon receiving a NACK.
+         */
+        fence = kmalloc(sizeof(*fence), GFP_KERNEL);
+        if (!fence) {
+                msg->payload[0] = ep->remote_ep;
+                msg->uop = SCIF_WAIT_NACK;
+                scif_nodeqp_send(ep->remote_dev, msg);
+                return;
+        }
+
+        /* Prepare the fence request */
+        memcpy(&fence->msg, msg, sizeof(struct scifmsg));
+        INIT_LIST_HEAD(&fence->list);
+
+        /* Insert to the global remote fence request list */
+        mutex_lock(&scif_info.fencelock);
+        atomic_inc(&ep->rma_info.fence_refcount);
+        list_add_tail(&fence->list, &scif_info.fence);
+        mutex_unlock(&scif_info.fencelock);
+
+        schedule_work(&scif_info.misc_work);
+}
+
+/**
+ * scif_recv_wait_resp: Handle SCIF_WAIT_(N)ACK messages.
+ * @msg:        Interrupt message
+ *
+ * The peer has responded to a SCIF_WAIT message.
+ */
+void scif_recv_wait_resp(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        struct scif_fence_info *fence_req =
+                (struct scif_fence_info *)msg->payload[1];
+
+        mutex_lock(&ep->rma_info.rma_lock);
+        if (msg->uop == SCIF_WAIT_ACK)
+                fence_req->state = OP_COMPLETED;
+        else
+                fence_req->state = OP_FAILED;
+        mutex_unlock(&ep->rma_info.rma_lock);
+        complete(&fence_req->comp);
+}
+
+/**
+ * scif_recv_sig_local: Handle SCIF_SIG_LOCAL request
+ * @msg:        Interrupt message
+ *
+ * The peer has requested a signal on a local offset.
+ */
+void scif_recv_sig_local(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        int err;
+
+        err = scif_prog_signal(ep, msg->payload[1], msg->payload[2],
+                               SCIF_WINDOW_SELF);
+        if (err)
+                msg->uop = SCIF_SIG_NACK;
+        else
+                msg->uop = SCIF_SIG_ACK;
+        msg->payload[0] = ep->remote_ep;
+        scif_nodeqp_send(ep->remote_dev, msg);
+}
+
+/**
+ * scif_recv_sig_remote: Handle SCIF_SIGNAL_REMOTE request
+ * @msg:        Interrupt message
+ *
+ * The peer has requested a signal on a remote offset.
+ */
+void scif_recv_sig_remote(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        int err;
+
+        err = scif_prog_signal(ep, msg->payload[1], msg->payload[2],
+                               SCIF_WINDOW_PEER);
+        if (err)
+                msg->uop = SCIF_SIG_NACK;
+        else
+                msg->uop = SCIF_SIG_ACK;
+        msg->payload[0] = ep->remote_ep;
+        scif_nodeqp_send(ep->remote_dev, msg);
+}
+
+/**
+ * scif_recv_sig_resp: Handle SCIF_SIG_(N)ACK messages.
+ * @msg:        Interrupt message
+ *
+ * The peer has responded to a signal request.
+ */
+void scif_recv_sig_resp(struct scif_dev *scifdev, struct scifmsg *msg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)msg->payload[0];
+        struct scif_fence_info *fence_req =
+                (struct scif_fence_info *)msg->payload[3];
+
+        mutex_lock(&ep->rma_info.rma_lock);
+        if (msg->uop == SCIF_SIG_ACK)
+                fence_req->state = OP_COMPLETED;
+        else
+                fence_req->state = OP_FAILED;
+        mutex_unlock(&ep->rma_info.rma_lock);
+        complete(&fence_req->comp);
+}
+
+static inline void *scif_get_local_va(off_t off, struct scif_window *window)
+{
+        struct page **pages = window->pinned_pages->pages;
+        int page_nr = (off - window->offset) >> PAGE_SHIFT;
+        off_t page_off = off & ~PAGE_MASK;
+
+        return page_address(pages[page_nr]) + page_off;
+}
+
+static void scif_prog_signal_cb(void *arg)
+{
+        struct scif_status *status = arg;
+
+        dma_pool_free(status->ep->remote_dev->signal_pool, status,
+                      status->src_dma_addr);
+}
+
+static int _scif_prog_signal(scif_epd_t epd, dma_addr_t dst, u64 val)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        struct dma_chan *chan = ep->rma_info.dma_chan;
+        struct dma_device *ddev = chan->device;
+        bool x100 = !is_dma_copy_aligned(chan->device, 1, 1, 1);
+        struct dma_async_tx_descriptor *tx;
+        struct scif_status *status = NULL;
+        dma_addr_t src;
+        dma_cookie_t cookie;
+        int err;
+
+        tx = ddev->device_prep_dma_memcpy(chan, 0, 0, 0, DMA_PREP_FENCE);
+        if (!tx) {
+                err = -ENOMEM;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                goto alloc_fail;
+        }
+        cookie = tx->tx_submit(tx);
+        if (dma_submit_error(cookie)) {
+                err = (int)cookie;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                goto alloc_fail;
+        }
+        dma_async_issue_pending(chan);
+        if (x100) {
+                /*
+                 * For X100 use the status descriptor to write the value to
+                 * the destination.
+                 */
+                tx = ddev->device_prep_dma_imm_data(chan, dst, val, 0);
+        } else {
+                status = dma_pool_alloc(ep->remote_dev->signal_pool, GFP_KERNEL,
+                                        &src);
+                if (!status) {
+                        err = -ENOMEM;
+                        dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                                __func__, __LINE__, err);
+                        goto alloc_fail;
+                }
+                status->val = val;
+                status->src_dma_addr = src;
+                status->ep = ep;
+                src += offsetof(struct scif_status, val);
+                tx = ddev->device_prep_dma_memcpy(chan, dst, src, sizeof(val),
+                                                  DMA_PREP_INTERRUPT);
+        }
+        if (!tx) {
+                err = -ENOMEM;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                goto dma_fail;
+        }
+        if (!x100) {
+                tx->callback = scif_prog_signal_cb;
+                tx->callback_param = status;
+        }
+        cookie = tx->tx_submit(tx);
+        if (dma_submit_error(cookie)) {
+                err = -EIO;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                goto dma_fail;
+        }
+        dma_async_issue_pending(chan);
+        return 0;
+dma_fail:
+        if (!x100)
+                dma_pool_free(ep->remote_dev->signal_pool, status,
+                              status->src_dma_addr);
+alloc_fail:
+        return err;
+}
+
+/*
+ * scif_prog_signal:
+ * @epd - Endpoint Descriptor
+ * @offset - registered address to write @val to
+ * @val - Value to be written at @offset
+ * @type - Type of the window.
+ *
+ * Arrange to write a value to the registered offset after ensuring that the
+ * offset provided is indeed valid.
+ */
+int scif_prog_signal(scif_epd_t epd, off_t offset, u64 val,
+                     enum scif_window_type type)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        struct scif_window *window = NULL;
+        struct scif_rma_req req;
+        dma_addr_t dst_dma_addr;
+        int err;
+
+        mutex_lock(&ep->rma_info.rma_lock);
+        req.out_window = &window;
+        req.offset = offset;
+        req.nr_bytes = sizeof(u64);
+        req.prot = SCIF_PROT_WRITE;
+        req.type = SCIF_WINDOW_SINGLE;
+        if (type == SCIF_WINDOW_SELF)
+                req.head = &ep->rma_info.reg_list;
+        else
+                req.head = &ep->rma_info.remote_reg_list;
+        /* Does a valid window exist? */
+        err = scif_query_window(&req);
+        if (err) {
+                dev_err(scif_info.mdev.this_device,
+                        "%s %d err %d\n", __func__, __LINE__, err);
+                goto unlock_ret;
+        }
+
+        if (scif_is_mgmt_node() && scifdev_self(ep->remote_dev)) {
+                u64 *dst_virt;
+
+                if (type == SCIF_WINDOW_SELF)
+                        dst_virt = scif_get_local_va(offset, window);
+                else
+                        dst_virt =
+                        scif_get_local_va(offset, (struct scif_window *)
+                                          window->peer_window);
+                *dst_virt = val;
+        } else {
+                dst_dma_addr = __scif_off_to_dma_addr(window, offset);
+                err = _scif_prog_signal(epd, dst_dma_addr, val);
+        }
+unlock_ret:
+        mutex_unlock(&ep->rma_info.rma_lock);
+        return err;
+}
+
+static int _scif_fence_wait(scif_epd_t epd, int mark)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        dma_cookie_t cookie = mark & ~SCIF_REMOTE_FENCE;
+        int err;
+
+        /* Wait for DMA callback in scif_fence_mark_cb(..) */
+        err = wait_event_interruptible_timeout(ep->rma_info.markwq,
+                                               dma_async_is_tx_complete(
+                                               ep->rma_info.dma_chan,
+                                               cookie, NULL, NULL) ==
+                                               DMA_COMPLETE,
+                                               SCIF_NODE_ALIVE_TIMEOUT);
+        if (!err)
+                err = -ETIMEDOUT;
+        else if (err > 0)
+                err = 0;
+        return err;
+}
+
+/**
+ * scif_rma_handle_remote_fences:
+ *
+ * This routine services remote fence requests.
+ */
+void scif_rma_handle_remote_fences(void)
+{
+        struct list_head *item, *tmp;
+        struct scif_remote_fence_info *fence;
+        struct scif_endpt *ep;
+        int mark, err;
+
+        might_sleep();
+        mutex_lock(&scif_info.fencelock);
+        list_for_each_safe(item, tmp, &scif_info.fence) {
+                fence = list_entry(item, struct scif_remote_fence_info,
+                                   list);
+                /* Remove fence from global list */
+                list_del(&fence->list);
+
+                /* Initiate the fence operation */
+                ep = (struct scif_endpt *)fence->msg.payload[0];
+                mark = fence->msg.payload[2];
+                err = _scif_fence_wait(ep, mark);
+                if (err)
+                        fence->msg.uop = SCIF_WAIT_NACK;
+                else
+                        fence->msg.uop = SCIF_WAIT_ACK;
+                fence->msg.payload[0] = ep->remote_ep;
+                scif_nodeqp_send(ep->remote_dev, &fence->msg);
+                kfree(fence);
+                if (!atomic_sub_return(1, &ep->rma_info.fence_refcount))
+                        schedule_work(&scif_info.misc_work);
+        }
+        mutex_unlock(&scif_info.fencelock);
+}
+
+static int _scif_send_fence(scif_epd_t epd, int uop, int mark, int *out_mark)
+{
+        int err;
+        struct scifmsg msg;
+        struct scif_fence_info *fence_req;
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+
+        fence_req = kmalloc(sizeof(*fence_req), GFP_KERNEL);
+        if (!fence_req) {
+                err = -ENOMEM;
+                goto error;
+        }
+
+        fence_req->state = OP_IN_PROGRESS;
+        init_completion(&fence_req->comp);
+
+        msg.src = ep->port;
+        msg.uop = uop;
+        msg.payload[0] = ep->remote_ep;
+        msg.payload[1] = (u64)fence_req;
+        if (uop == SCIF_WAIT)
+                msg.payload[2] = mark;
+        spin_lock(&ep->lock);
+        if (ep->state == SCIFEP_CONNECTED)
+                err = scif_nodeqp_send(ep->remote_dev, &msg);
+        else
+                err = -ENOTCONN;
+        spin_unlock(&ep->lock);
+        if (err)
+                goto error_free;
+retry:
+        /* Wait for a SCIF_WAIT_(N)ACK message */
+        err = wait_for_completion_timeout(&fence_req->comp,
+                                          SCIF_NODE_ALIVE_TIMEOUT);
+        if (!err && scifdev_alive(ep))
+                goto retry;
+        if (!err)
+                err = -ENODEV;
+        if (err > 0)
+                err = 0;
+        mutex_lock(&ep->rma_info.rma_lock);
+        if (err < 0) {
+                if (fence_req->state == OP_IN_PROGRESS)
+                        fence_req->state = OP_FAILED;
+        }
+        if (fence_req->state == OP_FAILED && !err)
+                err = -ENOMEM;
+        if (uop == SCIF_MARK && fence_req->state == OP_COMPLETED)
+                *out_mark = SCIF_REMOTE_FENCE | fence_req->dma_mark;
+        mutex_unlock(&ep->rma_info.rma_lock);
+error_free:
+        kfree(fence_req);
+error:
+        return err;
+}
+
+/**
+ * scif_send_fence_mark:
+ * @epd: end point descriptor.
+ * @out_mark: Output DMA mark reported by peer.
+ *
+ * Send a remote fence mark request.
+ */
+static int scif_send_fence_mark(scif_epd_t epd, int *out_mark)
+{
+        return _scif_send_fence(epd, SCIF_MARK, 0, out_mark);
+}
+
+/**
+ * scif_send_fence_wait:
+ * @epd: end point descriptor.
+ * @mark: DMA mark to wait for.
+ *
+ * Send a remote fence wait request.
+ */
+static int scif_send_fence_wait(scif_epd_t epd, int mark)
+{
+        return _scif_send_fence(epd, SCIF_WAIT, mark, NULL);
+}
+
+static int _scif_send_fence_signal_wait(struct scif_endpt *ep,
+                                        struct scif_fence_info *fence_req)
+{
+        int err;
+
+retry:
+        /* Wait for a SCIF_SIG_(N)ACK message */
+        err = wait_for_completion_timeout(&fence_req->comp,
+                                          SCIF_NODE_ALIVE_TIMEOUT);
+        if (!err && scifdev_alive(ep))
+                goto retry;
+        if (!err)
+                err = -ENODEV;
+        if (err > 0)
+                err = 0;
+        if (err < 0) {
+                mutex_lock(&ep->rma_info.rma_lock);
+                if (fence_req->state == OP_IN_PROGRESS)
+                        fence_req->state = OP_FAILED;
+                mutex_unlock(&ep->rma_info.rma_lock);
+        }
+        if (fence_req->state == OP_FAILED && !err)
+                err = -ENXIO;
+        return err;
+}
+
+/**
+ * scif_send_fence_signal:
+ * @epd - endpoint descriptor
+ * @loff - local offset
+ * @lval - local value to write to loffset
+ * @roff - remote offset
+ * @rval - remote value to write to roffset
+ * @flags - flags
+ *
+ * Sends a remote fence signal request
+ */
+static int scif_send_fence_signal(scif_epd_t epd, off_t roff, u64 rval,
+                                  off_t loff, u64 lval, int flags)
+{
+        int err = 0;
+        struct scifmsg msg;
+        struct scif_fence_info *fence_req;
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+
+        fence_req = kmalloc(sizeof(*fence_req), GFP_KERNEL);
+        if (!fence_req) {
+                err = -ENOMEM;
+                goto error;
+        }
+
+        fence_req->state = OP_IN_PROGRESS;
+        init_completion(&fence_req->comp);
+        msg.src = ep->port;
+        if (flags & SCIF_SIGNAL_LOCAL) {
+                msg.uop = SCIF_SIG_LOCAL;
+                msg.payload[0] = ep->remote_ep;
+                msg.payload[1] = roff;
+                msg.payload[2] = rval;
+                msg.payload[3] = (u64)fence_req;
+                spin_lock(&ep->lock);
+                if (ep->state == SCIFEP_CONNECTED)
+                        err = scif_nodeqp_send(ep->remote_dev, &msg);
+                else
+                        err = -ENOTCONN;
+                spin_unlock(&ep->lock);
+                if (err)
+                        goto error_free;
+                err = _scif_send_fence_signal_wait(ep, fence_req);
+                if (err)
+                        goto error_free;
+        }
+        fence_req->state = OP_IN_PROGRESS;
+
+        if (flags & SCIF_SIGNAL_REMOTE) {
+                msg.uop = SCIF_SIG_REMOTE;
+                msg.payload[0] = ep->remote_ep;
+                msg.payload[1] = loff;
+                msg.payload[2] = lval;
+                msg.payload[3] = (u64)fence_req;
+                spin_lock(&ep->lock);
+                if (ep->state == SCIFEP_CONNECTED)
+                        err = scif_nodeqp_send(ep->remote_dev, &msg);
+                else
+                        err = -ENOTCONN;
+                spin_unlock(&ep->lock);
+                if (err)
+                        goto error_free;
+                err = _scif_send_fence_signal_wait(ep, fence_req);
+        }
+error_free:
+        kfree(fence_req);
+error:
+        return err;
+}
+
+static void scif_fence_mark_cb(void *arg)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)arg;
+
+        wake_up_interruptible(&ep->rma_info.markwq);
+        atomic_dec(&ep->rma_info.fence_refcount);
+}
+
+/*
+ * _scif_fence_mark:
+ *
+ * @epd - endpoint descriptor
+ * Set up a mark for this endpoint and return the value of the mark.
+ */
+int _scif_fence_mark(scif_epd_t epd, int *mark)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        struct dma_chan *chan = ep->rma_info.dma_chan;
+        struct dma_device *ddev = chan->device;
+        struct dma_async_tx_descriptor *tx;
+        dma_cookie_t cookie;
+        int err;
+
+        tx = ddev->device_prep_dma_memcpy(chan, 0, 0, 0, DMA_PREP_FENCE);
+        if (!tx) {
+                err = -ENOMEM;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                return err;
+        }
+        cookie = tx->tx_submit(tx);
+        if (dma_submit_error(cookie)) {
+                err = (int)cookie;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                return err;
+        }
+        dma_async_issue_pending(chan);
+        tx = ddev->device_prep_dma_interrupt(chan, DMA_PREP_INTERRUPT);
+        if (!tx) {
+                err = -ENOMEM;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                return err;
+        }
+        tx->callback = scif_fence_mark_cb;
+        tx->callback_param = ep;
+        *mark = cookie = tx->tx_submit(tx);
+        if (dma_submit_error(cookie)) {
+                err = (int)cookie;
+                dev_err(&ep->remote_dev->sdev->dev, "%s %d err %d\n",
+                        __func__, __LINE__, err);
+                return err;
+        }
+        atomic_inc(&ep->rma_info.fence_refcount);
+        dma_async_issue_pending(chan);
+        return 0;
+}
+
+#define SCIF_LOOPB_MAGIC_MARK 0xdead
+
+int scif_fence_mark(scif_epd_t epd, int flags, int *mark)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        int err = 0;
+
+        dev_dbg(scif_info.mdev.this_device,
+                "SCIFAPI fence_mark: ep %p flags 0x%x mark 0x%x\n",
+                ep, flags, *mark);
+        err = scif_verify_epd(ep);
+        if (err)
+                return err;
+
+        /* Invalid flags? */
+        if (flags & ~(SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER))
+                return -EINVAL;
+
+        /* At least one of init self or peer RMA should be set */
+        if (!(flags & (SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER)))
+                return -EINVAL;
+
+        /* Exactly one of init self or peer RMA should be set but not both */
+        if ((flags & SCIF_FENCE_INIT_SELF) && (flags & SCIF_FENCE_INIT_PEER))
+                return -EINVAL;
+
+        /*
+         * Management node loopback does not need to use DMA.
+         * Return a valid mark to be symmetric.
+         */
+        if (scifdev_self(ep->remote_dev) && scif_is_mgmt_node()) {
+                *mark = SCIF_LOOPB_MAGIC_MARK;
+                return 0;
+        }
+
+        if (flags & SCIF_FENCE_INIT_SELF)
+                err = _scif_fence_mark(epd, mark);
+        else
+                err = scif_send_fence_mark(ep, mark);
+
+        if (err)
+                dev_err(scif_info.mdev.this_device,
+                        "%s %d err %d\n", __func__, __LINE__, err);
+        dev_dbg(scif_info.mdev.this_device,
+                "SCIFAPI fence_mark: ep %p flags 0x%x mark 0x%x err %d\n",
+                ep, flags, *mark, err);
+        return err;
+}
+EXPORT_SYMBOL_GPL(scif_fence_mark);
+
+int scif_fence_wait(scif_epd_t epd, int mark)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        int err = 0;
+
+        dev_dbg(scif_info.mdev.this_device,
+                "SCIFAPI fence_wait: ep %p mark 0x%x\n",
+                ep, mark);
+        err = scif_verify_epd(ep);
+        if (err)
+                return err;
+        /*
+         * Management node loopback does not need to use DMA.
+         * The only valid mark provided is 0 so simply
+         * return success if the mark is valid.
+         */
+        if (scifdev_self(ep->remote_dev) && scif_is_mgmt_node()) {
+                if (mark == SCIF_LOOPB_MAGIC_MARK)
+                        return 0;
+                else
+                        return -EINVAL;
+        }
+        if (mark & SCIF_REMOTE_FENCE)
+                err = scif_send_fence_wait(epd, mark);
+        else
+                err = _scif_fence_wait(epd, mark);
+        if (err < 0)
+                dev_err(scif_info.mdev.this_device,
+                        "%s %d err %d\n", __func__, __LINE__, err);
+        return err;
+}
+EXPORT_SYMBOL_GPL(scif_fence_wait);
+
+int scif_fence_signal(scif_epd_t epd, off_t loff, u64 lval,
+                      off_t roff, u64 rval, int flags)
+{
+        struct scif_endpt *ep = (struct scif_endpt *)epd;
+        int err = 0;
+
+        dev_dbg(scif_info.mdev.this_device,
+                "SCIFAPI fence_signal: ep %p loff 0x%lx lval 0x%llx roff 0x%lx rval 0x%llx flags 0x%x\n",
+                ep, loff, lval, roff, rval, flags);
+        err = scif_verify_epd(ep);
+        if (err)
+                return err;
+
+        /* Invalid flags? */
+        if (flags & ~(SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER |
+                        SCIF_SIGNAL_LOCAL | SCIF_SIGNAL_REMOTE))
+                return -EINVAL;
+
+        /* At least one of init self or peer RMA should be set */
+        if (!(flags & (SCIF_FENCE_INIT_SELF | SCIF_FENCE_INIT_PEER)))
+                return -EINVAL;
+
+        /* Exactly one of init self or peer RMA should be set but not both */
+        if ((flags & SCIF_FENCE_INIT_SELF) && (flags & SCIF_FENCE_INIT_PEER))
+                return -EINVAL;
+
+        /* At least one of SCIF_SIGNAL_LOCAL or SCIF_SIGNAL_REMOTE required */
+        if (!(flags & (SCIF_SIGNAL_LOCAL | SCIF_SIGNAL_REMOTE)))
+                return -EINVAL;
+
+        /* Only Dword offsets allowed */
+        if ((flags & SCIF_SIGNAL_LOCAL) && (loff & (sizeof(u32) - 1)))
+                return -EINVAL;
+
+        /* Only Dword aligned offsets allowed */
+        if ((flags & SCIF_SIGNAL_REMOTE) && (roff & (sizeof(u32) - 1)))
+                return -EINVAL;
+
+        if (flags & SCIF_FENCE_INIT_PEER) {
+                err = scif_send_fence_signal(epd, roff, rval, loff,
+                                             lval, flags);
+        } else {
+                /* Local Signal in Local RAS */
+                if (flags & SCIF_SIGNAL_LOCAL) {
+                        err = scif_prog_signal(epd, loff, lval,
+                                               SCIF_WINDOW_SELF);
+                        if (err)
+                                goto error_ret;
+                }
+
+                /* Signal in Remote RAS */
+                if (flags & SCIF_SIGNAL_REMOTE)
+                        err = scif_prog_signal(epd, roff,
+                                               rval, SCIF_WINDOW_PEER);
+        }
+error_ret:
+        if (err)
+                dev_err(scif_info.mdev.this_device,
+                        "%s %d err %d\n", __func__, __LINE__, err);
+        return err;
+}
+EXPORT_SYMBOL_GPL(scif_fence_signal);